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| United States Patent |
6,210,266
|
|
Barton
|
April 3, 2001
|
Pressure relief valve and method of manufacturing the same
Abstract
A flap-type pressure relief valve for venting of pressure out of, for
example, an automobile passenger compartment has a flap assembly
manufactured by a co-molding operation and inserted into a valve housing
to block the flow of air therethrough. The valve flap assembly includes a
flap carrier frame formed from a relatively rigid plastic in the first
shot of a two-shot co-molding process, and at least one flap formed from a
relatively flexible plastic in the second shot. The co-molding joins the
flap to a first perimeter wall of the frame along an edge of the flap, and
the flap is sufficiently flexible to bend about a line adjacent the edge.
In a two flap version, a second flap co-molded into connection with a
second perimeter wall of the frame. The resulting flap assembly can be
easily connected with the separately-molded valve housing by securing the
frame to the housing such that the flaps are positioned over valve seat
within the housing. The flaps are co-molded into connection with the frame
such that when the frame is secured to the housing to position the flaps
over the air passages, the flaps are bent away from the as-molded
configurations, thereby generating elastic force urging the flaps toward
the respective valve seats. The flaps can have rigid plastic stiffeners
co-molded into connection therewith. The stiffeners are preferably formed
simultaneously with the frame in the first shot of the co-molding process.
| Inventors:
|
Barton; Richard J. (Port Huron, MI)
|
| Assignee:
|
Sarnamotive Blue Water, Inc. (Marysville, MI)
|
| Appl. No.:
|
268607 |
| Filed:
|
March 15, 1999 |
| Current U.S. Class: |
454/162; 137/855 |
| Intern'l Class: |
B60H 001/26 |
| Field of Search: |
454/162,164,165
137/855,852,859
|
References Cited
U.S. Patent Documents
| 4702156 | Oct., 1987 | Sano.
| |
| 4781106 | Nov., 1988 | Frien.
| |
| 5105731 | Apr., 1992 | Kraus | 454/162.
|
| 5105849 | Apr., 1992 | Clough.
| |
| 5194038 | Mar., 1993 | Klomhaus et al. | 454/162.
|
| 5263895 | Nov., 1993 | Kraus et al. | 454/162.
|
| 5355910 | Oct., 1994 | Gies et al. | 454/162.
|
| 5419739 | May., 1995 | Lewis.
| |
| 5492505 | Feb., 1996 | Bell et al. | 454/162.
|
| 5601117 | Feb., 1997 | Lewis et al.
| |
| 5759097 | Jun., 1998 | Bernoville et al.
| |
| 5823870 | Oct., 1998 | Emerling et al. | 454/162.
|
| 5904618 | May., 1999 | Lewis | 454/162.
|
| Foreign Patent Documents |
| 2273153 | Jun., 1994 | GB.
| |
| 2273456 | Jun., 1994 | GB.
| |
| 2330793 | May., 1999 | GB.
| |
| WO 95/30528 | Nov., 1995 | WO.
| |
Primary Examiner: Joyce; Harold
Attorney, Agent or Firm: Young & Basile, P.C.
Claims
What is claimed is:
1. A valve flap assembly for a pressure relief valve having a housing with
at least one valve seat disposed adjacent a surface edge defining at least
one interior passage, the assembly comprising:
a flap carrier frame separate from the housing and formed of a first
relatively rigid plastic material, the frame including at least one member
having a first wall extendible along at least a portion of a perimeter of
the passage through the housing, the frame securable to the housing
adjacent to the passage such that the first wall is adjacent to the
surface edge of the passage; and
a flap formed of a second relatively pliable plastic material and having a
hinge edge co-molded into connection with the first wall of the frame, the
flap bendable about a line adjacent the hinge edge.
2. The valve flap assembly of claim 1 wherein the flap extends toward an
interior of the frame.
3. The valve flap assembly of claim 1 wherein the flap is co-molded into
connection with the flap carrier frame in a first configuration such that
securing of the flap carrier frame to the housing urges the flap into
contact with the valve seat surrounding the passage and said contact bends
the flap away from the first configuration to a second configuration, said
bending generating an elastic force urging the flap toward the valve seat.
4. The valve flap assembly of claim 1 further comprising a second flap
formed of the second plastic material and having a hinge edge co-molded
into connection with a second wall generally parallel with the first wall,
the second flap bendable about a line adjacent the hinge edge.
5. The valve flap assembly of claim 4 wherein the first flap extends toward
an interior of the frame and the second flap extends toward an exterior of
the frame.
6. The valve flap assembly of claim 1 wherein the flap carrier frame has a
plurality of bosses integrally molded therewith and extending therefrom
for insertion through respective apertures in the housing to retain the
flap carrier frame in connection with the housing.
7. The valve flap assembly of claim 1 wherein the flap has a generally
planar central portion and a seal portion surrounding the central portion
along all edges other than the hinge edge, and at least a part of the seal
portion is curved out of a plane defined by the central portion.
8. A valve flap assembly for a pressure relief valve having a housing
defining at least one interior passage, the assembly comprising:
a flap carrier frame formed of a first relatively rigid plastic material
and having a plurality of perimeter walls, the frame securable to the
housing to surround the passage such that the perimeter walls are adjacent
edges of the passage;
a flap formed of a second relatively pliable plastic material and having a
hinge edge co-molded into connection with a first of the perimeter walls,
the flap bendable about a line adjacent the hinge edge; and
at least one flap stiffener co-molded into connection with the flap.
9. The valve flap assembly of claim 8 wherein the flap stiffener comprises
an elongated first segment extending generally parallel to the hinge edge
of the flap and a second segment extending generally perpendicular to the
first segment.
10. A one-way pressure relief valve for use in an automotive vehicle
comprising:
a housing defining at least one interior passage and having a valve seat
surrounding a periphery of the passage;
a flap carrier frame formed of a first relatively rigid plastic material
separate from the frame and secured to the housing to surround the
passage, the frame having first and second spaced, generally parallel
perimeter walls extending adjacent respective opposite edges of the
passage; and
a flap formed of a second relatively pliable plastic material and having a
hinge edge co-molded into connection with the first perimeter wall of the
frame and depending therefrom such that the flap contacts the valve seat
of the passage and is bendable adjacent the hinge edge allowing the flap
to move away from the valve seat.
11. The valve of claim 10 wherein the flap is co-molded into connection
with the flap carrier frame in a first configuration, and when the flap
carrier frame is secured to the housing the flap is deflected to a second
configuration by contact with the valve seat, said bending generating an
elastic force urging the flap toward the valve seat.
12. The valve of claim 10 further comprising:
the housing having a second passage with a corresponding second valve seat;
and
a second flap formed of the second plastic material and having a hinge edge
co-molded into connection with the second perimeter wall of the frame and
depending therefrom such that the second flap contacts the valve seat of
the second passage and is bendable adjacent the hinge edge allowing the
flap to move away from the valve seat.
13. The valve of claim 12 wherein the first and second flaps are co-molded
into connection with the flap carrier frame in a first configuration, and
when the flap carrier frame is secured to the housing the flaps are
deflected to a second configuration by contact with each respective valve
seat, said bending generating an elastic force urging the flaps toward the
respective valve seats.
14. The valve of claim 10 wherein the flap carrier frame has a plurality of
bosses extending through respective apertures in the housing, and ends of
the bosses distal from the flap carrier frame are flared outwardly to
retain the flap carrier frame in connection with the housing.
15. The valve of claim 10 wherein the flap has a generally planar central
portion and a seal portion surrounding the central portion along all edges
other than the hinge edge, and at least a part of the seal portion is
curved out of a plane defined by the central portion and toward the valve
seat.
16. A one-way pressure relief valve for use in an automotive vehicle
comprising:
a housing defining at least one interior passage and having a valve seat
surrounding a periphery of the passage;
a flap carrier frame formed of a first relatively rigid plastic material
and secured to the housing to surround the passage, the frame having first
and second spaced, generally parallel perimeter walls extending adjacent
respective opposite edges of the passage;
a flap formed of a second relatively pliable plastic material and having a
hinge edge co-molded into connection with the first perimeter wall of the
frame and depending therefrom such that the flap contacts the valve seat
of the passage and is bendable adjacent the hinge edge so that the flap
may move away from the valve seat; and
at least one flap stiffener co-molded into connection with the flap.
17. The valve of claim 16 wherein the flap stiffener comprises an elongated
first segment extending generally parallel to the edge of the flap and a
second segment extending generally perpendicular to the first segment.
18. A method of forming a valve flap assembly for use in a pressure relief
valve having a housing with at least one valve seat disposed adjacent a
surface edge defining at least one passage formed therethrough, the method
comprising the steps of:
in a first shot of a two-shot co-molding process, injection molding a flap
carrier frame from a relatively rigid plastic material, the frame
securable to the housing adjacent to the passage; and
in a second shot of the co-molding process, injection molding a flap from a
relatively flexible plastic material such that an edge of the flap is
joined to the frame along a first perimeter wall of the frame.
19. The method of claim 18 wherein the first shot of the co-molding process
further forms at least one flap stiffener such that the flap is molded
into connection with the flap stiffener.
20. The method of claim 19 wherein the flap carrier is formed as a frame
having a substantially continuous perimeter, and the flap is molded
substantially within the perimeter of the flap carrier frame.
21. The method of claim 18 wherein a second flap is formed in the second
shot of the co-molding process such that an edge of the second flap is
joined to a second perimeter wall of the flap carrier frame, the second
perimeter wall being spaced from and generally parallel with the first
perimeter wall.
22. The method of claim 21 wherein the frame comprises first and second
spaced, generally parallel perimeter walls and the first flap is joined to
the first perimeter wall and the second flap is joined to the second
perimeter wall.
23. A valve flap assembly manufactured according to the method of claim 18,
the assembly comprising:
a flap carrier frame formed of a relatively rigid plastic material, the
frame securable to the housing adjacent to the passage; and
a flap formed of a relatively flexible plastic material such that an edge
of the flap is joined to the frame along a first wall of the frame.
24. The valve flap assembly of claim 23 further comprising:
a hinge edge co-molded into connection with the first wall, the flap
bendable about a line adjacent the hinge edge.
25. A method of forming a pressure relief valve comprising the steps of:
forming a valve housing defining at least one internal passage;
in a first shot of a two-shot co-molding process, injection molding a flap
carrier frame and at least one flap stiffener from a first relatively
rigid plastic material, the flap stiffener comprising a first segment
extending generally parallel to an edge of the frame and a second segment
extending generally perpendicular to the first segment;
in a second shot of the co-molding process, injection molding at least one
flap from a second relatively flexible plastic material, the flap having a
edge contacting the flap carrier frame to join the flap to the flap
carrier frame, and the flap contacting the stiffener and joined thereto;
and
securing the flap carrier frame to the valve housing to position the flap
over the internal passage.
26. The method of claim 23 wherein the step of securing the flap carrier
frame to the valve housing deflects the flap from an as-molded position to
thereby generate an elastic force urging the flap toward a closed position
covering the internal passage.
27. The method of claim 23 wherein the first shot of the co-molding process
further forms a second flap stiffener adjacent to and outside of the
frame, and the second shot of the co-molding process further forms a
second flap contacting the second flap stiffener to join the second flap
to the second flap stiffener and having an edge contacting the flap
carrier frame to join the second flap to the flap carrier frame.
28. The method of claim 23 wherein the frame comprises first and second
spaced, generally parallel perimeter walls and the first and second flaps
are molded to be joined to the first and second perimeter walls
respectively.
29. A valve flap assembly for a pressure relief valve having a housing
defining at least one interior passage, the assembly manufactured by a
process comprising the steps of:
injection molding a flap carrier frame from a first relatively rigid
plastic material and having a plurality of perimeter walls, the frame
securable to the housing to surround the passage such that the perimeter
walls are adjacent edges of the passage; and
injection molding at least one flap from a second relatively pliable
plastic material such that a hinge edge of the at least one flap is
co-molded into connection with a first of the perimeter walls, the flap
bendable about a line adjacent the hinge edge.
30. The valve flap assembly of claim 23 wherein the flap extends toward an
interior of the frame.
31. The valve flap assembly of claim 23 wherein the flap is co-molded into
connection with the flap carrier frame in a first configuration so that
securing of the flap carrier frame to the housing urges the flap into
contact with a valve seat surrounding the passage and said contact bends
the flap away from the first configuration to a second configuration, said
bending generating an elastic force urging the flap toward the valve seat.
32. The valve flap assembly of claim 23 further comprising a second flap
formed of the second plastic material and having a hinge edge co-molded
into connection with a second wall generally parallel with the first wall,
the second flap bendable about a line adjacent the hinge edge.
33. The valve flap assembly of claim 32 wherein the first flap extends
toward an interior of the frame and the second flap extends toward an
exterior of the frame.
34. The valve flap assembly of claim 23 further comprising at least one
flap stiffener co-molded into connection with the flap.
35. The valve flap assembly of claim 34 wherein the flap stiffener
comprises an elongated first segment extending generally parallel to the
hinge edge of the flap and a second segment extending generally
perpendicular to the first segment.
36. The valve flap assembly of claim 23 wherein the flap carrier frame has
a plurality of bosses integrally molded therewith and extending therefrom
for insertion through respective apertures in the housing to retain the
flap carrier frame in connection with the housing.
37. The valve flap assembly of claim 23 wherein the flap has a generally
planar central portion and a seal portion surrounding the central portion
along all edges other than the hinge edge, and at least a part of the seal
portion is curved out of a plane defined by the central portion.
38. The valve flap assembly of claim 28 wherein the flap carrier frame is
separate from the housing, the frame including at least one member having
a first wall extendible along at least a portion of a perimeter of the
passage through the housing, the frame securable to the housing adjacent
to the passage such that the first wall is adjacent to the surface edge of
the passage.
39. A valve flap assembly for use in a pressure relief valve having a
housing with at least one valve seat disposed adjacent a surface edge
defining at least one passage formed therethrough, the assembly
comprising:
a flap carrier frame injection molded in a first shot of a two-shot
co-molding process from a relatively rigid plastic material, the frame
securable to the housing adjacent to the passage; and
a flap injection molded in a second shot of the co-molding process from a
relatively flexible plastic material such that an edge of the flap is
joined to the frame along a first wall of the frame.
40. The valve flap assembly of claim 39 wherein at least one flap stiffener
is injection molded in the first shot of the co-molding process such that
the flap is molded into connection with the flap stiffener.
41. The valve flap assembly of claim 40 wherein the flap carrier is formed
as a frame having a substantially continuous perimeter, and the flap is
molded substantially within the perimeter of the flap carrier frame.
42. The valve flap assembly of claim 39 wherein a second flap is formed in
the second shot of the co-molding process such that an edge of the second
flap is joined to a second perimeter wall of the flap carrier frame, the
second perimeter wall being spaced from and generally parallel with the
first perimeter wall.
43. The valve flap assembly of claim 42 wherein the frame comprises first
and second spaced, generally parallel perimeter walls and the first flap
is joined to the first perimeter wall and the second flap is joined to the
second perimeter wall.
44. The valve flap assembly of claim 39 wherein the flap carrier frame is
separate from the housing, the frame including at least one member having
a first wall extendible along at least a portion of a perimeter of the
passage through the housing, the frame securable to the housing adjacent
to the passage such that the first wall is adjacent to the surface edge of
the passage.
Description
FIELD OF THE INVENTION
This invention relates generally to one-way pressure relief valves, and in
particular to such a valve for use in conjunction with a ventilation
system for a passenger compartment of an automotive vehicle.
BACKGROUND OF THE INVENTION
One-way, flap-type pressure relief valves are commonly used in applications
such as vehicle ventilation systems. Typically, the valve serve to relieve
over-pressure that can occur within a nearly air-tight passenger
compartment of a vehicle when, for example, a door of the vehicle is
rapidly closed, while preventing the entry of air from outside the vehicle
into the passenger compartment.
Valves used for this purpose generally include a frame or housing for
mounting within an aperture formed in a panel enclosing the passenger
compartment and defining an air passageway through the panel. The housing
has one or more internal valve seats over which a plurality of valve flaps
lie. The flaps include relatively thin, flexible members and overlie the
valve seats on a side of the housing facing exterior of the passenger
compartment. Each flap is fixed to the housing along one peripheral edge.
When an over-pressure condition occurs within the passenger compartment,
the air pressure forces the flaps to move away from the valve seats,
bending or hinging adjacent the fixed edge to allow air to flow through
the air passageway out of the passenger compartment. When the air pressure
has equalized on both sides of the valve or when the pressure on the
exterior becomes greater, the flaps swing or bend back to engage the valve
seats and block airflow into the passenger compartment.
Valves of this general type are often manufactured by injection molding the
housing and the valve flaps as separate pieces and then joining the two
components by any one of several different methods. U.S. Pat. No.
5,601,117 teaches that apertures formed along an edge of the flap are
placed over pins projecting from the corresponding portion of the housing.
The ends of the pins are then flattened to form locking caps which secure
the flap over the pin. U.S. Pat. No. 5,419,739 discloses a valve flap in
the form of a flexible sheet having integrally formed tabs which are
forced through respective slots formed in the housing. Each of these
various methods of construction has inherent disadvantages, generally
related to the fact that producing separate components that must be
assembled with one another is time consuming and/or labor intensive, thus
making the valve relatively expensive to manufacture.
U.S. Pat. No. 5,355,910 discloses a valve having a flap element formed by
extruding a sheet of relatively soft, flexible elastomeric material, and
simultaneously extruding one or more strips of relatively rigid plastic
onto the surface of the sheet. A first of the strips provides a rigid
mounting strip for bolting or otherwise joining the valve element to an
associated valve housing. A second of the rigid strips can be formed to
extend across the width of the flap adjacent the opposite edge thereof to
prevent the valve element from warping or deforming during use. The gap
between the mounting strip and the stiffening strip forms a flexible hinge
where the flap bends to move between closed and open positions. The
continuous extrusion is sheared to the length required for use in a valve
assembly, and apertures are formed through the mounting strip so that the
flap can be secured to the valve housing.
The extrusion technique requires the rigid strip to extend the full width
of the flexible sheet and be a constant thickness and height. The
extrusion technique is also unable to produce a plurality of flaps joined
together in a top-to-bottom arrangement so that the flaps can then be
attached to the valve housing in a single assembly step.
SUMMARY OF THE INVENTION
The present invention provides a valve flap assembly for use with a
pressure relief valve which is efficiently and inexpensively produced by a
co-molding operation and retains a flexible flap within a rigid frame for
attachment to a valve housing. The invention further provides a flap
structure that is sufficiently stiff to maintain a desired shape during
use.
In accordance with one aspect of the invention, a valve flap assembly
includes a relatively rigid flap carrier frame having a plurality of
perimeter walls and a relatively flexible flap co-molded into connection
with a first perimeter wall of the frame. The flap is joined to the
perimeter wall along a hinge edge and is sufficiently flexible to bend
about a line adjacent the hinge edge. The resulting flap assembly can be
easily connected with a valve housing defining at least one air passage by
securing the flap carrier frame to the housing such that a frame surrounds
the passage, thus positioning the flap over a valve seat surrounding the
passage.
According to a further aspect of the invention, the flap is co-molded into
connection with the flap carrier frame in a configuration such that when
the flap carrier frame is secured to the housing to position the flap over
the air passage, the flap is bent away from the as-molded configuration as
the flap comes into contact with the valve seats. This bending generates
an elastic force urging the flap toward the valve seat in order to help to
ensure that the valve flap closes completely and positively when pressure
across the valve has equalized.
In accordance with another feature of the invention, the valve flap
assembly includes first and second flaps co-molded into connection with
respective first and second perimeter walls of the frame. The first and
second walls are parallel with one another so that the frame can be
secured to the valve housing to position the flaps over adjacent air
passages of the housing. This provides a multi-flap assembly that can be
attached to the valve housing as a single unit, thereby reducing
manufacturing cost and complexity.
In accordance with a further aspect of the invention, at least one of the
flexible flaps has stiffeners co-molded into connection therewith. The
stiffeners are preferably formed simultaneously with the flap carrier
frame in the first shot of the co-molding process, and the flap is
subsequently molded so as to contact and be joined to the stiffener as
well as the frame. Each of the stiffeners preferably includes an elongated
first segment extending generally parallel to the hinge edge of the flap,
and a second segment extending generally perpendicular to the first
segment. This construction allows stiffening material to be added to the
otherwise flexible flap only in the locations necessary, thus saving
material and cost while achieving the desired flap stiffness.
In the embodiment of the flap valve assembly depicted herein, the flap
carrier frame is molded to include a plurality of bosses extending
therefrom which are inserted through apertures formed in the valve
housing. The ends of the bosses distal from the flap carrier may then be
flared outwardly by a heat staking process to retain the flap carrier in
connection with the housing.
According to another aspect of the invention, a method is provided for
producing a valve flap assembly for use in a pressure relief valve, the
method including a two-shot co-molding process wherein the first shot
forms a flap carrier frame from a relatively rigid plastic material, and
the second shot forms a flap from a relatively flexible plastic material
such that an edge of the flap is joined to the frame along a first
perimeter wall of the frame. The use of the co-molding process allows
formation of a flap carrier having a substantially continuous perimeter
such that the flap can be molded substantially within the perimeter of the
frame, and the frame can then be secured to a valve housing to surround an
air passage and locate the flap over the passage.
In the preferred embodiment of the method, two flaps are formed by the
second shot, one of the flaps attached to each of two parallel perimeter
walls of the frame. The resulting flap assembly formed by this method is a
unitary, multi-flap assembly which can be joined to a valve housing in a
single operation to position the flaps over respective air passages
through the housing.
Also in a preferred embodiment of the method, a flap stiffener is formed
substantially simultaneously with the frame in the first shot of the
co-molding process. When the flap is formed in the second shot, the flap
contacts the stiffener and is joined to both the stiffener and the frame.
The use of the co-molding process allows formation of a flexible flap
having a stiffener which extends only over selected portions of the flap
surface so that a required degree of flap stiffness can be achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of a pressure relief valve according
to the present invention;
FIG. 2 is an assembly view of the pressure relief valve of FIG. 1;
FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 2;
FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 1;
FIG. 5 is a second embodiment of a valve flap assembly according to the
invention and;
FIG. 6 is a third embodiment of a valve flap assembly according to the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1-4, a pressure relief valve 10 according to the present
invention is of the type typically used in conjunction with the
ventilation system of an automotive vehicle. The valve includes a housing
12 that fits into an aperture formed in a panel enclosing the vehicle's
passenger compartment, and a valve flap assembly 14 which is mounted
internally to the housing 12 and controls the flow of air (or other gases)
into and out of the passenger compartment.
The housing 12 includes an outer shell 16 having a flange 18 extending
outwardly therefrom around its entire perimeter. A middle wall 20 extends
horizontally across the approximate center of the housing 12 to define
separate upper and lower air passages through the housing 12. The interior
of the outer shell 16 and the middle wall 20 define upper and lower valve
seat surfaces 22 surrounding the respective air passages. As best seen in
FIG. 3, the valve seats 22 are disposed at an angle to the vertical. A
panel seal 24 is preferably disposed on the housing flange 18 and is
formed of a relatively flexible plastic material.
The valve flap assembly 14 includes a valve carrier frame 26 formed of a
relatively rigid plastic material, such as polypropylene, polystyrene or
polyvinyl chloride. In the preferred embodiment of the invention, the
frame 26 is generally rectangular in shape, including parallel upper and
lower perimeter walls 26a,26b connected by left and right perimeter walls
26c,26d. A plurality of pin-like bosses 28 project from the upper and
lower perimeter walls of the frame 26 and are preferably molded integrally
with the frame.
An upper and a lower flap 30,32 are attached along the respective uppermost
edges to the upper 26a and lower perimeter walls 26b respectively. The
flaps 30,32 are formed of a relatively pliable plastic material, such as
thermoplastic elastomer, by a co-molding process which joins the flaps to
the frame 26.
As used herein, the term co-molding refers to a well-known injection
molding process in which a quantity of a first fluid material is injected
into a first mold cavity formed by a pair of dies, allowed to at least
partially solidify, then the dies are moved relative to one another to
create a second mold cavity which is only partially filled by the first
material. A second quantity of a second fluid thermoplastic material is
injected into the second mold cavity, coming into contact with the
solidified first material so that when the second material sets the two
quantities of material are physically joined to one another. The
co-molding process allows a single, integral part to be formed from two or
more different types of plastic material in a single mold, with no further
assembly steps required.
Each flap 30,32 has a stiffener 34 joined to and overlaying a portion of
its surface. The stiffeners 34 are made of a relatively rigid plastic
material, preferably the same as that used for the frame 26. In a
preferred embodiment of the invention, each stiffener 34 includes a first
elongated segment 34a extending substantially parallel to the lower edge
of the flap and a second segment 34b extending substantially perpendicular
to the first segment along the vertical center line of the flap. The
stiffener 34 can contact the surface of the flap, or the stiffener can be
embedded in and partially or completely surrounded by the material of the
flap.
Each flap 30,32 has a generally planar central portion and a peripheral
seal portion 30a,32a surrounding the central portion along all edges other
than the hinge edge. According to the preferred embodiment of the
invention, the seal portion 30a,32a is slightly curved out of the plane
defined by the central portion (see FIG. 4). When viewed in cross-section,
the seal portions 30a,32a taper off in thickness, coming to a point at
their tips.
In the embodiment of the flap shown in FIGS. 1-4, the flap is of a uniform
thickness over its entire area except for thickened sections 36 extending
adjacent the lateral edges of the flap. These thickened sections 36 serve
as flow channels during the injection molding process, aiding the flow of
the liquid thermoplastic material throughout the mold cavity. The
thickened sections 36 also add somewhat to the stiffness of the flap.
The stiffeners 34 are preferably formed during the first shot of the
co-molding process, substantially simultaneously with the flap carrier
frame 26. In this way, the formation of the flaps 30,32 during a second
shot co-molds the flaps into connection with both the carrier frame 26 and
the stiffeners 34.
The valve flap assembly 14 is joined with the valve housing 12 such that
the flap carrier frame 26 surrounds the upper air passage and the upper
and lower flaps 30,32 overlay the valve seats 22 surrounding the upper and
lower air passages respectively. The flap carrier frame 26 is retained in
connection with the housing 12 by inserting the bosses 28 through
apertures 38 formed in corresponding positions in the housing 12 and
subsequently deforming the ends of the bosses distal from the frame by,
for example, heat staking.
When the valve flap assembly 14 is installed in the housing 12, the upper
and lower flaps 30,32 are forced to bend away from the respective
as-molded positions (shown in FIG. 4) such that the flaps lie in contact
with the respective valve seats 22 (see FIG. 3). This bending of the valve
flaps 30,32 creates an elastic force urging the flaps back toward the
as-molded positions and hence into contact with the respective valve seats
22. The embodiment of the valve depicted herein is designed for
installation in a generally vertical panel, so that the valves slope
downwardly from the hinged edges as the valves rest on the valve seats 22.
It is also possible to design a valve according to the present invention
for installation in a panel oriented horizontally or at any angle.
The curved ends of the seal portions 30a,32a improve the quality of the
seal between the flaps 30,32 and the valve seats 22. Further, the curved
seal portions result in quieter operation of the valve, substantially
eliminating any "slapping" noise that would otherwise be produced as a
completely flat flap meets the valve seat when the flap swings to the
closed position.
As viewed in FIG. 3, the interior of the vehicle passenger compartment is
on the left of the valve. When the pressure inside the passenger
compartment rises above that outside of the compartment, such as when a
door of the vehicle is closed suddenly, the air pressure exerts force on
the surfaces of the flaps 30,32, causing the flaps to bend about the
respective hinge edges where the flaps are joined to the flap carrier
frame 26. The flaps 30,32 swing upwardly and away from the respective
valve seats 22 thus allowing the pressure inside the passenger compartment
to vent to the outside until the pressure has equalized. The flaps 30,32
then swing back into contact with the valve seats 22 to close off the air
passages, thus preventing the flow of air or any other gases into the
passenger compartment. When the pressure inside and outside of the
passenger compartment has equalized, the flaps 30,32 return to the seated
and closed positions due to a combination of gravity acting on the flaps
and the elastic force caused by the flaps bending upward and away from the
as-molded positions.
The flexible plastic material used for the flaps 30,32 is advantageous
because the material allows the flaps 30,32 to bend between the closed and
open positions, and also because the material provides a better seal
between the flap and valve seat when in the closed position. The flexible
material, however, may tend to warp or deform during use so that the flap
no longer makes contact with the valve seat around the entire perimeter of
the air passage. The flap stiffeners 34 attached to the valve surfaces
reduce or prevent this type of warping and so prolong the useful life and
increase the effectiveness of the valve. The co-molding process allows the
stiffeners 34 to be formed in any shape and covering any area or areas of
the flap surface as necessary to prevent unwanted warping.
Many different configurations for the stiffeners 34 are possible. FIG. 5
depicts a flap assembly having stiffeners 40 which differ from those of
FIGS. 1-4 in having two additional side segments 42 extending adjacent the
lateral edges of the flap. Each flap of the embodiment shown in FIG. 6 has
two separate H-shaped stiffeners 44, each including a first segment 46
extending generally horizontally across the flap and additional segments
48 extending perpendicular thereto at either end of the first segment.
While the invention has been described in connection with what is presently
considered to be the most practical and preferred embodiment, it is to be
understood that the invention is not to be limited to the disclosed
embodiments but, on the contrary, is intended to cover various
modifications and equivalent arrangements included within the spirit and
scope of the appended claims, which scope is to be accorded the broadest
interpretation so as to encompass all such modifications and equivalent
structures as is permitted under the law.
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